Guar and its derivatives are the most commonly used gelling agents in fracturing treatments. In the last few years, enormous price swings and supply shortages of guar have posed major challenges for service companies and operators. In addition, the fluid volumes in fracturing treatments have increased substantially, while water supply has become more of a public concern. Rather than paying to treat and dispose of produced and flowback water, operators would like to recycle it in subsequent stimulation operations. Carboxymethylcellulose (CMC) has been recommended as an effective alternative to guar system. However, CMC system can only be crosslinked under low pH environment and their application is limited with formation temperature up to 250°F and also in high quality water.

A readily available polysaccharide, Carboxymethylhydroxyethylcellulose (CMHEC) is presented in this paper to address the challenges of making a fracturing fluid in harsh reservoir conditions like high formation temperature and high-TDS produced water. Using a produced water sample with TDS over 200,000 ppm and total hardness as CaCO3 over 40,000 ppm as representative water, laboratory testing has demonstrated that the new polymer can be fully hydrated within 3 minutes, similar to the hydration rate of guar in fresh water. Furthermore, the resulting linear gel can be crosslinked with metal crosslinkers to achieve excellent rheology at various formation temperatures. The crosslink can also be delayed to minimize pipe friction. The fluid is compatible with other common stimulation additives, including scale inhibitors. Conventional oxidizing breakers can be used to effectively break down the fluids, leaving no formation or proppant pack damage.

This paper will discuss the evolution of the technology and present rheology results at various formation conditions.

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